<html>
<head>
<title>alert对话框</title>
<script type="text/javascript">
function disp_alert()
{
	alert("请输入姓名!")
}
</script>

</head>
<body>
	<FORM>
		姓名：<input type=text id=username>
		<input type="button" onclick="disp_alert()" value="提交" id="submit">
	</FORM>
</body>
</html>
